With rapid development of electronic and information industries, computers and the peripheral device thereof become essential parts in our daily lives. In addition to the working purposes, computers can be employed as amusement tools. In the computer systems, input devices play important roles for communicating the computer and the user. The common input devices of the computer systems are for examples keyboards. For helping the user well operate the computer, many novel keyboards are developed in views of humanization and user-friendliness.
Generally, a keyboard has a plurality of key structures. FIG. 1 is a schematic exploded view illustrating a key structure of a keyboard according to the prior art. As shown in FIG. 1, the key structure 1 comprises a keycap 11, a scissors-type connecting member 12, an elastic element 13, a membrane switch 14 and a base plate 15. The keycap 11 could be depressed by a user. The keycap 11 is connected with the scissors-type connecting member 12. The scissors-type connecting member 12 comprises an inner frame 121 and an outer frame 122. The scissors-type connecting member 12 is connected with the keycap 11 and the base plate 15. The inner frame 121 has two inner frame pivot rods 1211. Corresponding to the inner frame pivot rods 1211, two outer frame pivot holes 1221 are formed in the outer frame 122. The inner frame pivot rods 1211 are pivotally coupled with the outer frame pivot holes 1221 such that the inner frame 121 is rotatable with respect to the outer frame 122. The membrane switch 14 is arranged on the base plate 15. The elastic element 13 is arranged between the keycap 11 and the membrane switch 14. When the keycap 11 is depressed, the elastic element 13 is deformed downwardly to trigger the membrane switch 14 such that the membrane switch 14 generates an electronic signal. After these components 11, 12, 13 and 14 are combined together, a resulting configuration of the key structure 1 is shown in FIG. 2.
In a case that the keycap 11 is not depressed, the keycap 11 is located at a first height. Whereas, when the keycap 11 is depressed, a depressing force is exerted on the keycap 11 and the elastic element 13 is compressed in response to the depressing force. As the keycap 11 is depressed, the inner frame 121 and the outer frame 122 of the scissors-type connecting member 12 are rotated such that the inner frame 121 and the outer frame 122 are parallel with each other. At the same time, the membrane switch 14 on the base plate 15 is triggered to generate an electronic signal. In addition, the keycap 11 is lowered from the first height to a second height. The difference between the first height and the second height indicates the travel distance of the key structure 1.
In a case that the depressing force exerted on the keycap 11 is eliminated, the keycap 11 will be moved upwardly due to the restoring force of the elastic element 13. As the keycap 11 is moved upwardly, the inner frame 121 and the outer frame 122 are transmitted by the keycap 11 to rotate. As such, the keycap 11 is returned to its original position at the first height. In designing the scissors-type connecting member 12, the keycap 11 needs to be returned to its original position after the depressing force exerted on the keycap 11 is eliminated. Generally, the elastic element 13 provides the restoring force to push the keycap 11 back to its original position. Moreover, the inner frame 121 and the outer frame 122 need to cooperate with each other in order to precisely control the upward moving action of the keycap 11. In other words, the configurations of the inner frame 121 and the outer frame 122 are very important factors that influence the quality and the use life of the key structure 1.
For combining the inner frame 121 with the outer frame 122, the user needs to prop open the outer frame 122 to widen the distance between the two outer frame pivot holes 1221, which are formed in bilateral sides of the outer frame 122. As such, the inner frame pivot rods 1211 could be successfully inserted into corresponding outer frame pivot holes 1221 so as to combine the inner frame 121 and the outer frame 122 together. The procedure of propping-open the outer frame 122 increases the assembling time of the key structure 1 and is detrimental to the throughput of the keyboard. On the other hand, if the external force used to prop open the outer frame 122 is improper, the outer frame 122 is readily damaged or distorted. Under this circumstance, the yield is reduced and the fabricating cost is increased. Moreover, since the outer frame 122 has the outer frame pivot holes 1221, the outer frame 122 becomes weak and is easily damaged. In other words, the scissors-type connecting member 12 is not suitable for slimness of the key structure 1.
Therefore, there is a need of providing an improved key structure with a scissors-type connecting member so as to obviate the drawbacks encountered from the prior art.